Sjögren's syndrome occurs in two basic forms: primary Sjögren's syndrome -- the disease by itself and not associated with any other illness; and secondary Sjögren's syndrome -- disease that develops in the presence of another autoimmune disease such as rheumatoid arthritis, lupus, or vasculitis.
As many as four million people in the U.S. have Sjögren's syndrome. More than 90% of them are women. The disease can affect people of any race or age, although the average age of onset is in the late 40s.